How to prevent the user from leaving the profile?

Question

PHP

I have wordpress+buddypress.
After the user registers, I redirect them to the buddypress profile edit page. And I want that he could not save his profile until he fills in some fields.
Check the fields for fullness is clear as:

<?php
$bpProfileField = bp_get_profile_field_data( 'field=fieldName&user_id=' .    $userid );
if ( empty ( $bpProfileField) ):
?>

And how to prevent the user from leaving this page?

Answer 1

Firstly, this is bad practice, and secondly, nothing.